Electrode for electromedical equipment



Oct. 6, 1964 G. H. SULLIVAN ELEcTRonE FOR ELECTROMEDICAL EQUIPMENT Filed July 17, 1961 F IG. 4

FIG. I2

N Rm MU VS mH. nn m G Fifi!! ATTORN United States Patent O 3,151,519 ELECTRDE EUR ELECTRGMEDICAL EQUEEMENT Gearge H. Sulhvan, Sherman Galia, Calif., assigner to Spaeelah, Ine., Van Nuys, Calif., a eorpuraticn of Salifornia Filed July 17, 1961, Ser. No. 124,599 9 Claims. (El. 2128-417) rIhis invention relates to a skin contact electrode and more particularly to a disposable electrode for use with eleotromedical equipment which may be attached directly to the skin to provide a low resistance contact therewith and which does not require the use of externally applied means for holding the electrode in place.

The present invention has reference to electromedical apparatus such as electroencephalographs, electrocardiographs, and the like, which requires attachment of an electrode and an interconnecting leadwire between the skin surface of a body under `test and the test equipment. Heretofore, it has generally been necessary to employ cumbersome bands, clamps, xftures or other mechanical means for holding the electrode in close Contact with the skin. Attempts to employ an adhesive to hold the electrode in contact with the skin have not been entirely satisfactory owing to the diihculty in applying the exact quantity of adhesive to the skin and/or the electrode, required to make an adequate bond, without interfering with the electrical contact. Furthermore, the application of adhesives directly on the skin is unpleasant to the patient and is generally untidy. At best, such attempts are unduly time-consuming, particularly when a large number of electrodes must be applied.

In order to provide a low resistance contact between an electrode and the skin, pads moistened with an electrolyte or a conductive paste are often interposed between the electrode and the skin. Heretofore, it has been the practice to apply the electrode paste directly to the skin and thereafter, apply the electrode over the area to which the paste is applied. A lead-wire connection to the electrode is then made by means of a clip or other attachment. This procedure is both time consuming and costly. Moistening of the pad or applying the paste, in addition to being both time consuming and messy, is also costly. These and other shortcomings of prior electrode application techniques are overcome by the present invention which contemplates improved means for holding electrodes in close contact with the skin when in use and improved means for the retention of an electrolyte in contact with an electrode both prior to, and during use.

These difficulties are overcome by providing the electrode with a self-contained quantity of electrolyte paste confined within a surrounding band or strip of pressuresensitive adhesive, on the under surface of the electrode, for directly bonding the electrode to the skin of the patient.

It is therefore a principal object of the invention to provide an electrode for direct application to a body surface and having a self-contained electrolyte surrounded by a pressure-sensitive adhesive seal to facilitate direct attachment to the body surface.

Another object of the invention is to provide a selfcontained, disposable electrode which is low in cost, and simple to use.

Another difficulty experienced in connection with electrodes of the type contemplated in the present invention, relates to the establishment of good electrical contact over an irregular surface.

Therefore, it is also an object of the present invention to provide a tissue contact electrode which adapts itself to the irregular surfaces of the tissues against which it is applied, while at the same time maintaining electrical 3,15 1,6 19 Fatented Oct. 6, 1 964 lCe contact substantially coextensive with the area of the electrode.

A further object is to provide an electrode of simple and inexpensive construction which may be applied at will to various portions of the body so as to provide wide and uniform contact therewith.

Still another object of the invention is the improvement of electrodes for electromedical equipment generally.

These and other objects of the invention will more readily be understood upon review of the following speciiication, taken in conjunction with the drawings in which:

IGURE l is a perspective view `of a preferred embodiment of the invention shown prior .rto application.

FIGURE 2 is a cross sectional view taken along line 2-2 of FIGURE l.

FIGURE 3 shows the method of removal of the protective web from the apparatus of FIGURE 2.

FIGURE 4 is a cross sectional view showing the device of FIGURE 3 applied to the surface of the patients skin.

FIGURE 5 illustrates an alternative shape of the electrode layer.

FIGURE 6 shows the bottom surface of the electrode after the protective web has been removed.

FIGURE 7 is an elevational view illustrating an alternative embodiment of the protective web means.

FIGURE 8 illus-trates the method of removal lof the protective web means from the apparatus of FIGURE 7.

FIGURE 9 is a sectional view of a modified form of the invention employing an electrode layer comprising a metallized plastic iilm.

FIGURE l0 is a fragmentary plan view of the apparatus of FIGURE 9 illustrating an alternative method of attaching the lead wires to the electrode layer.

FIGURE ll is a perspective view illustrating an alternative embodiment of the invention employing a detachable lead connector.

FIGURE l2 is a perspective view showing a perforated strip for packaging the electrode.

The embodiment of the invention shown in FIGURE 1 comprises a disk-shaped layer fabricated from metal foil or the like, to which is attached a ilexible lead wire 2. Lead wire 2 is attached to the conductive layer 1 by soldering, riveting, or other suitable fastening means 3. Lead wire 2 may, if desired, have an insulating covering 5, as will be apparent to -those versed in the art.

The under side or bottom surface of the electrode has an annular ring of pressure-sensitive adhesive 4 for bonding the electrode to the skin or tissue surface to which it is to be attached. Adhesive 4 preferably is disposed in a closed path on the bottom surface of layer 1, adjacent to the edge thereof. The adhesive 4 should, preferably, be biologically inert so as not to irritate the skin to which it is applied. An adhesive suitable for this use is the cyanocrylic type. Located within the ring of adhesive 4 is a quantity of highly viscous electrolyte 6. This electrolyte 6 may comprise a saline paste or jelly commonly referred to as electrode paste. This paste exhibits good electrical conductivity and provides a low resistance path between the electrode layer 1 and the skin surface to which the electrode is attached.

Prior to application, the underside of the electrode carries an impermeable plastic lm or membrane 7 to maintain cleanliness of the contact surface of the electrode and to prevent the paste 6 from drying out. The membrane 7 extends beyond the outer edge of layer 1 and is held in place by adhesive 4. The adhesive 4 will make a better bond with Athe surface of layer 1 than it will with the surface of membrane 7, thus permitting membrane 7 to be stripped off without removing the adhesive 4 from layer 1. This plastic membrane 7 is peeled off immediately prior to usage, and the electrode is then pressed onto the skin 8 of the patient in a manner similar to the application of the well-known ready-made adhesive bandage. The ring of adhesive 4 bonds to the skin 8 and confines the electrolyte 6, which fiows over the skin surface to effect a low ohmic contact. After having served its purpose, the electrode may be removed merely by peeling it ofi, in which instance the lead-wire 2 may be used as a means by which the electrode may be pulled upward and away from the skin. The low cost and simplicity of the device permits it to be disposed of after usage.

While there has been shown in connection with FlG- URES 1-3 and 6 a foil contact layer which is disk-shaped or of circular area, it will be understood that this layer may, if desired, be formed in any desired pattern and/or may have other shapes. For example, there is shown in FIGURE 5, an embodiment wherein the electrode has an elongated or oval shape. The device may also be rectangular, free-form or other outline, as may be required for a specific application.

To facilitate removal of the protective membrane from the electrode prior to use, the protective membrane may be divided into two sections 9 and 1i?, each of which has an extended tab portion 9 and 19 adjoining each other at a line extending diametrically across the under surface of the electrode. Tab portions 9 and 16' may be grasped between the fingers of each hand and pulled apart, as shown in FIGURE 8, thus exposing the under surface of the electrode. This modification of the protective membrane minimizes handling of layer 1 and thus prevents damage thereto or undue distortion thereof.

As a further modification of the structure of the invention, it is contemplated that the metal layer 1 may be replaced by a highly fiexible conductive layer.

Looking now at FIGURE 9, the conductive backing layer of the electrode comprises a fiexible plastic sheet 12 which may be Tefion, Mylar, acetate or other suitable plastic materials, to one surface of which there is applied a very thin metallic film 13. Film 13 is electrically conductive and may be produced by metallizing or evaporating a metal film on the plastic substrate 12. Since the film 13 comprises a lamina on the underside of the electrode structure, a tab portion 14 is folded back upon the upper side as shown in FIGURES 9 and l0, thus providing a convenient location for the attachment of the lead Wire 15 to the conductive film 13. The lead wire 15 may be connected to the film 13 on tab 14 by soldering, riveting or other suitable fastening means 16. The remaining elements may be identical with those of the embodiment of FIGURE l; namely, adhesive 4, electrolyte 6, and membrane 7.

Still another modification of the basic electrode structure is shown in FIGURE 11. In certain instances, it may be desirable to have means for selectively connecting and disconnecting the lead wire from the electrode. Accordingly, there is provided an electrode layer 17 to which is attached a metal sleeve-like receptacle 1S into which may be inserted pin 19, dimensioned to fit snugly within receptacle 18. Lead wire 2Q is permanently attached to pin 19. An insulating sleeve 23 may be used to cover the junction between pin 19 and lead wire 20. Receptacle 18 may be soldered to layer 17 or attached thereto by other suitable means as will be obvious to those skilled in the art. Layer 17 is temporarily attached to protective membrance 21 by adhesive 22 as in the case of the above-described embodiment.

There is shown in VFIGURE l2 an individual packaging feature for convenient handling of the electrodes prior to use. The electrode 1 is supported on membrane 7 which in turn is carried on perforated strip 24. This comprises a so-called tear-off package in which paper strip 24 may be torn along perforations 25 in order to separate a single electrode and its protective peel-away membrane 7 from a Continuous STP Carrying a plurality of electrodes. As

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4 will be apparent to those skilled in the art, strip 24 may be formed into rolls to facilitate handling and dispensing. Also, a semi-rigid plastic bubble may be placed over the electrode and supported by strip 24 in order to further protect the electrode prior to use.

There has been shown and described, hereinabove, a self-contained, self-attaching electrode for use with electromedical equipment which is conveniently packaged and simple to use. Furthermore, the novel electrode of the present invention is sufiiciently low in cost to permit being disposed of after one-time use, thus preventing the possibility of spreading communicable skin disease. While there have been shown and described and pointed out the fundamental novel features of the invention as applied to preferred embodiments, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated and in their operation may be made by those skilled in the art. For example, the conductive layer of the electrode need not be a circular disk as shown in FIGURES 6 and ll, but may be of any other suitable shape, as determined by application requirements, including elongated strips, rectangles or ovals such as shown in FIGURE 5. Gther modifications will suggest themselves to those skilled in the art; therefore, it is intended that the invention be limited only as indicated by the scope of the following claims.

What is claimed is:

1. An electrode adapted for application to a body surface, comprising: a layer of flexible conductive material one surface of which is adapted for engagement with said body surface; an adhesive material applied to a portion of said one surface of said layer and dening a closed path adjacent the peripheral edge of said one surface; a viscous electrolyte located on said one surface within said closed path; an impermeable membrane semi-permanently bonded to said adhesive material, said membrane covering said electrolyte and extending beyond the peripheral edge of said layer of said conductive material, and flexible lead wire means connected to the surface of said conductive material opposite said one surface.

2. An electrode :adapted for application to a body surface, comprising: a layer of conductive foil, and adhesive material` applied to a portion of one surface of said layer and defining a closed path adjacent the peripheral edge of said one surface, :a viscous electrolyte located on said one surface within said closed path, lead wire means connected to said conductive foil, and first and second exible impermeable sheets adjacent said one surface and extending beyond said layer, said sheets each having an edge portion folded outward from said one surface, said folded edge portions meeting along a common line extending across said one surface.

3. A tissue contact electrode comprising: a foil disk, a fiexible lead wire attached to said disk, a strip of adhesive applied to a portion of one surface of said disk adjacent the edge thereof and extending in a closed path along the periphery of said one surface, a viscous electrolyte on said one surface and confined Within said strip of adhesive, and impermeable membrane means extending beyond said disk adjacent said one surface and detachably bonded to said adhesive strip.

4. tissue contact electrode as defined in claim 3, wherein said membrane means comprises first and second exrble sheets extending beyond said disk, said sheets each having an edge portion folded outward from said one surface, said folded edge portions meeting along a common line extending across said one surface.

5. A tissue Contact electrode comprising, a flexible plastic disk having a metal film lamina thereon, a flexible lead wire attached to said lamina, a viscous electrolyte located 1n the center of the exterior surface of said lamina, a ring ofpressure-sensitive adhesive on said lamina surrounding said electrolyte, and impermeable membrane means adjacent said electrolyte and detachably bonded to said adhesive ring. y y

6. An electrode adapted for application to a body surface comprising:

a disk of conductive foil;

a viscous electrolyte located in the center of one surface of said disk;

a ring of pressure-sensitive `adhesive on said one surface surrounding said electrolyte;

an impermeable membrane semi-permanently bonded to said adhesive ring, said membrane covering said electrolyte and extending beyond the periphery of said disk; and

lead Wire means connected to said disk.

7. An electrode as defined in claim 6, wherein said membrane comprises irst and second exible sheets, said sheets each having an edge portion folded outward from said one surface, said folded edge portion meeting along a common line extending across said one surface.

8. An article of manufacture comprising:

an elongated paper strip longitudinally divided into a plurality of separable areas by a plurality of transverse perforations;

an impermeable membrane carried on at least one surface of each of said separable areas;

a plurality of flexible foil disks equal in number to the number of said membranes;

a viscous electrolyte confined within the center portion of one surface of each of said disks;

a ring or" pressure-sensitive adhesive on said one surface of each of said disks surrounding said center portion and semi-permanently bonding each of said disks to a corresponding one of said membranes; and

a plurality of lead wire means, one each of which is connected to a corresponding one of said disks.

9. A tissue contact electrode comprising:

a laminar element having an upper layer of lleXible plastic and a coextensive lower layer of thin metal lm, said element having a generally circular shape and an extended tab portion folded back upon said upper layer;

flexible lead wire means :attached to the upwardly exposed metal lm surface of said folded tab portion;

a viscous electrolyte located in the center of the exterior surface of said lower layer;

a closed ring of pressure-sensitive adhesive surrounding said electrolyte and carried on the exterior surface of said lower layer; :and

impermeable membrane means covering said electrolyte and detachably bonded to said lower layer by said adhesive ring.

References Cited in the le of this patent UNITED STATES PATENTS 1,662,446 Wappler Mar. 13, 1928 2,547,487 Penny Apr. 3, 1951 2,872,926 Alderman Feb. 10, 1959 2,943,628 Howell July 5, 1960 FOREIGN PATENTS 498,527 Great Britain Jan. 10, 1939 

3. A TISSUE CONTACT ELECTRODE COMPRISING: A FOIL DISK, A FLEXIBLE LEAD WIRE ATTACHED TO SAID DISK, A STRIP OF ADHESIVE APPLIED TO A PORTION OF ONE SURFACE OF SAID DISK ADJACENT THE EDGE THEREOF AND EXTENDING IN A CLOSED PATH ALONG THE PERIPHERY OF SAID ONE SURFACE, A VISCOUS ELECTROLYTE ON SAID ONE SURFACE AND CONFINED WITHIN SAID STRIP OF ADHESIVE, AND IMPERMEABLE MEMBRANE MEANS EXTENDING BEYOND SAID DISK ADJACENT SAID ONE SURFACE AND DETACHABLY BONDED TO SAID ADHESIVE STRIP. 